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xiu                            SABRE-TOOTHED TIGERS                          401
form is sometimes, though quite unnecessarily., separated as O.
lanif/era. The genus occurs fossil in the Siwalik deposits of
India, the species being known as C. bracTiT/giiatha:
Fam. 2. Hadiaerodoatidae.—This is a family of totally-
extinct Cats which range from the Eocene down to the Pleistocene.
Their general structure is like that of the Felidae; but they
differ in a number of skeletal features. Thus there is an
alisphenoid canal, and, as in Bears, there is a postglenoid foramen.
There is also a distinct carotid foramen, which does not occur in
the true Cats. The teeth are often distinguished by the huge
size of the superior canines, which are " weapons for penetrating
wounds, without rival among carnivorous animals." These must
have been displayed at the sides of the chin when, the mouth
was closed, and it has even been suggested that the animal
possessing these exaggerated canines could hardly have properly
closed its mouth. The lower canines were often on the contrary
much reduced, and in fact incisor-like. In tracing the series of
these Cats we find a gradual reduction of the teeth from a more
nearly complete number down to the specialised dentition of. the
existing Cats. The genus Proaeluriis, Miocene in range, had
four premolars in each jaw, and two molats in the lower and one
in the upper. This is the greatest number of teeth found in any
member of the group.
The resemblance of this genus to Cryptoprocta has been
insisted upon. A.rchaelurus has suffered a reduction, since one
premolar in the lower jaw has disappeared, its formula being thus
^ % ® i -P111 lit M- i- The next stage is shown by Dinictis with
three premolars in both jaws. There are a good many species of
this genus -which are all American and Miocene. This genus has
five toes upon the hind-feet, and was probably plantigrade. It
had retractile claws.
In the genus Ni'm/rcu'vus the dental formula is still further
reduced. Another premolar of the lower jaw has gone, the
formula being thus I §- C -J- Pm -|- M ^-. JWimraiius gomphodiis
was a Carnivore about the size of a Panther. It has no third
trochanter upon the femur, which process is present in the
corresponding bone of Diwictis* JPogonodo'n was an equally
large animal in which the premolars were three in each
jaw, but the molars have become reduced to one in the
lower, as they have in this and other genera in the upper
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